1. Field of the Invention
This invention relates generally to radiant energy. More particularly, it relates to the inspection of inanimate objects employing a source of high intensity radiation and a photographic detector.
2. Prior Art
During the past 30 years, radiant energy photography (viz, radiograpy) has become the primary quality control testing procedure for a large number of industrial purposes. In particular, radiography has been extensively employed in the examination of surface irregularities and defects, poor welding joints, etc., in steel and other metal plates, hollow bodies, girders, and other such objects.
Although the industrial uses of radiography are indeed numerous, present techniques for making radiographs in a wet environment have been found unsatisfactory in a number of instances.
For example, in the oil and gas industry, which has a multitude of offshore installations (i.e., platforms and pipelines) throughout the world, there has been a longstanding need for an efficacious, economical process and device for radiographing such installations quickly and in situ on the ocean floor. In particular, the prior art processes and devices, as exemplified by U.S. Pat. Nos. 3,214,586 and 3,673,407, have been found wanting, in that they do not provide the necessary combination of (1) effective removal of attenuating fluid media in the area being radiographed and (2) facile execution of the process by a diver in the underwater environment. This is especially true in respect of the radiographing of a pipeline containing a liquid hydrocarbon product or a small-diameter hollow support member filled with sea water.
As a consequence, the examination of the soundness of such pipelines and structures has been often resisted entirely or postponed for long periods of time, because of the attending expenses and inconvenience. Accordingly, in view of the age of some of these pipelines and structures, an actual danger does exist that the structures will fail or the hydrocarbon products within the pipelines will enter and pollute territorial waters, as well as sources and potential sources of water supply for cities and towns.